Abstract 15817: Hemodynamics of the UNOS Heart Allocation System: Is it Time to Add Objectivity to an Subjective System?

Abstract

Introduction: In the current United States Organ Sharing heart transplant allocation system, hemodynamic criteria, systolic blood pressure (SBP), cardiac index (CI), and pulmonary capillary wedge pressure (PCWP), are utilized to justify certain listing statuses. Hypothesis: We sought to identify how currently utilized, and advanced, hemodynamics discriminated patients by listing status. Methods: Retrospective analysis of the Scientific Registry of Transplant Candidates including all adults listed for heart transplant since the updated listing criteria went live in October 2018 was completed. In addition to SBP, CI, and PCWP, the mean advanced hemodynamic metrics of aortic pulsatility index (API), cardiac power output (CPO), left ventricular stroke work index (LVSWI), right ventricular stroke work index (RVSWI), and pulmonary artery pulsatility index (PAPI), were calculated for each status. Results: Since October 2018, 9,418 patients were listed for heart transplant, and 8,636 had complete hemodynamic data at time of listing. Currently utilized hemodynamic metrics failed to discriminate lower acuity statuses (3 through 6 for PCWP and CI; 4 through 6 for SBP). For advanced hemodynamic metrics, mean API was lowest for Status 1 patients, and rose consistently with increasing status with a clear stepwise and statistically significant difference for sequential statuses (p < 0.001). CPO and LVSWI were unable to discriminate statuses 3-6. For right-sided hemodynamics, PAPI was unable to discriminate statuses 2 through 6, and there were no significant differences across any status for RVSWI. Conclusions: API is the only hemodynamic metric that is able to differentiate patients on the heart transplant waiting list across all active statuses by increasing in a stepwise fashion. Incorporation of API into future iterations of the UNOS heart allocation system may help better risk stratify patients and minimize waitlist mortality.